Method of producing a vacuum-tight joint of relatively thin parts



April 1966 e. CHOPINET ETAL 3,245,143

METHOD OF PRODUCING A VACUUM-TIGHT JOINT OF RELATIVELY THIN PARTS FiledAug. 9, 1962 lerrq, DUMON Guy Ofiop/nef ATTORNE United States Patent3,245,143 METHOD OF PRODUCING A VACUUM-TIGHT JOINT 0F RELATIVELY THINPARTS Guy Chopinet and Pierre Dumon, Paris, France, assignors t0CSF-Compagnie Generale de Telegraphic Sans Fil,

Paris, France Filed Aug. 9, 1962, Ser. No. 215,949 Claims priority,application France, Sept. 25, 1961,

74,05 13 Claims. (Cl. 29-486) The present invention relates to avacuum-tight joint or assembly of relatively thin pieces.

According to the known prior art technique, the end parts of such piecesare bent, the bent faces are then placed one against the other to causethe edges thereof suration) or of molybdenum-steel (danger of fragilephase).

The present invention aims at a method of assembling and joining byarc-auto-brazing relatively thin pieces, applicable successfully even ifthere exists metallurgical incompatibility between the metals used.

The method according to the present invention essentially consists inplacing the plane terminal portions of the pieces to be joined togetherone against the other, i.e., in a position facing each other, whileleaving a slight play therebetween in order to avoid stresses at themoment of fusion, and more particularly in such a manner that the edgeof one piece overlaps or extends beyond the edge of the other piece by acertain distance, and to cause melting by the use of an arc of theprojecting or overlapping edge while preventing melting of the otheredge, in such a manner that the former folds or flanges over the endface of the latter and is secured thereat by autobrazing.

Additionally, the method according to the present invention ischaracterized by the fact that, during the operation, the plane ofjunction of the two pieces to be assembled is maintained substantiallyin a position inclined to the horizontal plane, with the piece havingthe projecting or overlapping edge being arranged above the other piece.

Accordingly, it is an object of the present invention to provide amethod for establishing a vacuum-tight joint, especially between tworelatively thin pieces made of metallurgically incompatible materials,which effectively eliminates the shortcomings and inadequaciesencountered in the prior art.

Another object of the present invention resides in the provision of amethod for joining two pieces in a vacuumtight manner which avoids thedanger of cracking and/ or of a fragile phase between the two pieces.

A further object of the present invention resides in the provision of amethod which assures a satisfactory vacuum-tight joint between twopieces even if made of metallurgically incompatible materials.

3,245,143 Patented Apr. 12, 1966 A still further object of the presentinvention resides in the provision of a vacuum-tight joint, especiallybetween two relatively thin parts made of metallurgically incompatiblematerials, which may be obtained in a simple manner without requiringadditional material for the welded joint, for instance, byarc-auto-brazing.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description, whentaken in connection with the accompanying drawing, which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein FIGURE 1 is a cross-sectional viewthrough the two pieces to be joined prior to welding thereof, and

FIGURE 2 is a cross-sectional view similar to FIG- URE 1 through thesame pieces after welding thereof.

Referring now to the drawing, wherein like reference numerals are usedin the two figures to designate like parts, reference numerals 1 and 2generally designate therein the pieces, such as relatively thin metalsheets, to be joined, which are of a thickness e and of the same orderof magnitude. The plane terminal parts of the two pieces are positionedin such a manner as to face each other, while leaving therebetween asmall play of some tenths of a millimeter. The connecting or joiningplane of the two pieces is maintained, during the operation, at an angleor with respect to the horizontal plane, for example, of the order of 45The piece 1 is placed above piece 2 with the edge portion thereofoverlapping or extending beyond the opposite edge portion by a distanceh, slightly smaller than the thickness 2. The edge portion of piece 1 isthen caused to melt with the aid of the are, without, however, meltingthe edge portion of piece 2. The edge portion of piece 1 thereupon foldsor flanges over the end face of the edge portion of piece 2 and issecured thereto by auto-brazing. The joined assembly assumes theappearance shown in FIGURE 2.

While applicable to the welding of any similar or dissimilar metals, themethod according to the present invention is particularly advantageousin the application thereof to the joining of a relatively goodconductive metal to a relatively poor conductive metal, for example, forwelding copper to stainless steel, or steel to molybdenum, or copper tomolybdenum. In all of these cases, the methods known in the prior arthave proved to be either inoperative, or have given rise todisappointments after a shorter or longer period of time.

Thus, while we have shown and described one embodiment in accordancewith the present invention, it is understood that the same is notlimited thereto but is susceptible of many changes and modificationswithin the spirit and scope of the present invention and we, therefore,do not wish to be limited to the details shown and described herein butintend to cover all such changes and modifications as are encompassed bythe scope of the appended claims.

We claim:

1. A method of producing a vacuum-tight joint between two metal sheets,comprising the steps of placing at least the terminal portions of saidsheets to face each other with a small gap left therebetween in such amanner that the respective edge portions of the sheets are substantiallyparallel, the edge portion of one of the two sheets projecting beyondthe edge portion of the other sheet by a predetermined distance in theplane of said gap, and of melting only said projecting edge portionwhereby the molten metal of said one sheet folds over the unmolten edgeportion of said other sheet to be welded together by self-brazing.

2. A method of producing a vacuum-tight joint between two metal sheets,comprising the steps of placing at least the terminal portions of saidsheets to face each other with a small gap left therebetween in such amanner that the respective edge portions of said two sheets aresubstantially parallel, the edge portion of one of said sheetsprojecting beyond the edge portion of the other of said sheets by apredetermined distance in the plane of said gap, and of melting onlysaid projecting edge portion whereby the molten metal of said one sheetfolds over the unmolten edge portion of said other sheet to be weldedtogether by self-brazing, the projecting distance of the edge portion ofsaid one sheet being slightly smaller than the width of the sheets.

3. A method of producing a vacuum-tight joint between two metal sheets,comprising the steps of placing at least the terminal portions of saidsheets to face each other with a small gap left therebetween in such amanner that the respective edge portions of said sheets aresubstantially parallel, the edge portion of the one of said two sheetswhich is disposed above the edge portion of the other sheet extendsbeyond the edge portion of the said other sheet by a predetermineddistance in the plane of said gap, and of melting substantially only theextending edge portion whereby the molten metal of said one sheetflanges over the unmolten edge portion of said other sheet to be weldedtogether by self-brazing.

4. A method of producing a vacuum-tight joint between two metal sheets,comprising the steps of placing at least the terminal portions of saidsheets to face each other with a small gap left therebetween in such amanner that the respective edge portions of said sheets aresubstantially parallel and the plane of the gap is inclined to thehorizontal, the edge portion of the one of said two sheets which isdisposed above the edge portion of the other sheet extends beyond theedge portion of the said other sheet by a predetermined distance in theplane of said gap, and of melting substantially only the extending edgeportion whereby the molten metal of said one sheet flanges over theunmolten edge portion of said other sheet to be welded together byself-brazing.

5. A method of producing a vacuum-tight joint between two metal sheets,comprising the steps of placing at least the terminal portions of saidsheets to face each other with a small gap left therebetween in such amanner that the respective edge portions of said sheets aresubstantially parallel and the plane of the gap is inclined to thehorizontal by an angle of the order of 45 and that the edge portion ofthe one of said two sheets which is disposed above the edge portion ofthe other sheet extends beyond the edge portion of the said other sheetby a predetermined distance in the plane of said gap, and of meltingsubstantially only the extending edge portion whereby the molten metalof said one sheet flanges over the unmolten edge portion of said othersheet to be welded together by self-brazing.

6. A method of vacuum-tight joining together two relatively thinmetallic pieces, comprising the steps of positioning the end portions ofsaid pieces to face each other with a small gap therebetween in such amanner that the respective edge portions of said pieces aresubstantially parallel, the edge portion of one of said pieces extendingbeyond the edge portion of the other piece by a predetermined distancein the plane of said gap, melting primarily only said extending edgeportion to thereby fold the molten metal thereof over the substantiallyunmolten edge portion of said other piece, and welding together saidedge portions by self-brazing.

7. A method of vacuum-tight joining two metal pieces with one of saidpieces being of a relatively good conducting metal and the other of arelatively poor conducting metal, comprising the steps of placing atleast the terminal portions of said pieces to face each other with asmall gap therebetween in such a manner that the respective edgeportions of said pieces are substantially parallel, the edge portion ofone of said pieces extending beyond the edge portion of the other pieceby a predetermined distance in the plane of said gap, and of meltingsubstantially only said extending edge portion to thereby cause themolten metal of said one piece to flange over the substantially unmoltenedge portion of said other piece to be Welded together.

8. A method of vacuum-tight joining together two relatively thinmetallic pieces of metallurgically incompatible metals, comprising thesteps of positioning the end portions of said pieces to face each otherwith a small gap therebetween in such a manner that the respective edgeportions of said pieces are substantially parallel, the edge portion ofone of said pieces extending beyond the edge portion of the other pieceby a predetermined distance in the plane of said gap, and of meltingsubstantially only said extending edge portion to thereby fold themolten metal thereof over the edge portion of said other piece, andwelding together said edge portions.

9. A method of producing a vacuum-tight joint between two metal piecesmade of copper and stainless steel, respectively, comprising the stepsof placing at least the terminal portions of said pieces to face eachother with a small gap therebetween so that the respective edge portionsof said pieces are substantially parallel, the edge portion of one ofsaid pieces extending beyond the edge portion of the other piece by apredetermined distance in the plane of said gap, and of meltingsubstantially only said extending edge portion to thereby fold themolten metal of said one piece over the substantially unmolten edgeportion of said other piece to be welded together.

10. A method of producing a vacuum-tight joint between two metal piecesmade of stainless steel and molybdenum, respectively, comprising thesteps of placing at least the terminal portions of said pieces to faceeach other with a small gap therebetween so that the respective edgeportions of said pieces are substantially parallel, the edge portion ofone of said pieces extending beyond the edge portion of the other pieceby a predetermined distance in the plane of said gap, and of meltingsubstantially only said extending edge portion to thereby fold themolten metal of said one piece over the substantially unmolten edgeportion of said other piece to be welded together.

11. A method of producing a vacuum-tight joint between two metal piecesmade of copper and molybdenum, respectively, comprising the steps ofplacing at least the terminal portions of said pieces to face each otherwith a small gap therebetween so that the respective edge portions ofsaid pieces are substantially parallel, the edge portion of one of saidpieces extending beyond the edge portion of the other piece by apredetermined distance in the plane of said gap, and of meltingsubstantially only said extending edge portion to thereby fold themolten metal of said one piece over the substantially unmolten edgeportion of said other piece to be welded together.

12. A method of vacuum-tight joining together two relatively thinmetallic pieces of metallurgically incompatible metals, comprising thesteps of positioning the end portions of said pieces to face each otherwith a small gap therebetween with the plane thereof inclined to thehorizontal in such a manner that the respective edge portions of saidpieces are substantially parallel, the edge portion of the upper one ofsaid pieces extending beyond the edge portion of the other piece by apredetermined distance in the plane of said gap, and of melting substantially only said extending edge portion to thereby fold the molten metalthereof over the edge portion of said other piece, and welding togethersaid edge portions.

13. A method of vacuum-tight joining together two relatively thinmetallic pieces of metallurgically incompatible metals, comprising thesteps of positioning the end portions of said pieces to face each otherwith a small gap therebetween with the plane thereof inclined to thehorizontal in such a manner that the respective edge portions of saidpieces are substantially parallel, the edge portion of the upper one ofsaid pieces extending beyond the edge portion of the other piece by apredetermined distance in the plane of said gap, melting primarily onlysaid extending edge portion to thereby fold the molten metal thereofover the substantially unmolten edge portion of said other piece, andwelding together said edge portions.

References Cited by the Examiner UNITED STATES PATENTS Bartz 29-486Dunham 29-486 Adams et al 18936 Huntley et a1 29-199 X Adams 29-486 XKoontz 18936 Sheppard.

Stulen et a1 2948l X Trautvetter 29481 X Nijhuis et al 29-482 X JOHN F.CAMPBELL, Primary Examiner.

1. A METHOD OF PRODUCING A VACUUM-TIGHT JOINT BETWEEN TWO METAL SHEETS,COMPRISING THE STEPS OF PLACING AT LEAST THE TERMINAL PORTIONS OF SAIDSHEETS TO FACE EACH OTHER WITH A SMALL GAP LEFT THEREBETWEEN IN SUCH AMANNER THAT THE RESPECTIVE EDGE PORTIONS OF THE SHEETS ARE SUBSTANTIALLYPARALLEL, THE EDGE PORTION OF ONE OF THE TWO SHEETS PROJECTING BEYONDTHE EDGE PORTION OF THE OTHER SHEET BY A PREDETERMINED DISTANCE IN THEPLANE OF SAID GAP, AND OF MELTING ONLY SAID PROJECTING EDGE PORTIONWHEREBY THE MOLTEN METAL OF SAID ONE SHEET FOLDS OVER THE UNMOLTEN EDGEPORTION OF SAID OTHER SHEET TO BE WELDED TOGETHER BY SELF-BRAZING.